The standardization organization 3GPP (3rd Generation Partnership Project) has stated a work item called LTE (Log Term Evolution) to study a wireless access method, which is higher in data-rate transmission, short in delay, and packet-transmission oriented, as a successor of the third-generation mobile communication method such as W-CDMA or HSDPA/HSUPA (see Non-Patent Document 1 and Non-Patent Document 2).
The target communication speed of LTE is 100 Mbps-1 Gbps for the downlink, and 50 Mbps for the uplink. In LTE, the candidate for the FDD (Frequency Division Duplex) wireless method is OFDMA (Orthogonal Frequency Division Multiplexing) for the downlink, and SC-FDMA (Single Carrier Frequency Division Multiple Access) for the uplink. The use of those wireless methods requires the wireless base station to perform adaptive scheduling in both the frequency domain and the time domain.
If data is left stagnant in the transmission buffer in a mobile station on the uplink on which data is transmitted via SC-FDMA, the mobile station requests the wireless base station to allocate uplink resources. The wireless base station performs adaptive scheduling at a TTI (Transmit Time Interval), and sends the transmission permission signal (Signaling) to the mobile phone at a TTI. Upon receiving the transmission permission, the mobile station sends the data signal at the TTI. The mobile station sends the control signals such as Ack/Nack, CQI (Channel Quality Indicator), and MIMO (Multiple Input Multiple Output) parameter, periodically or at a predetermined timing.
When there is a data signal to be sent, the control signal described above is time-division multiplexed with the data signal on a physical channel called PUSCH (Physical Uplink Shared Channel). As this control signal that is time-division multiplexed, the standardization organization has almost reached a decision that the control information (Data Associated Signal), which is used to notify the transmission parameters of the data signal, be not used.